/Engine/Source/Runtime/Landscape/Classes/LandscapeComponent.h
Fills a layer to 100% on this component, adding it if needed and removing other layers that get painted away. Uses the edit layer specified by LandscapeEdit.
void FillLayer ( [ULandscapeLayerInfoObject](API\Runtime\Landscape\ULandscapeLayerInfoObject) * LayerInfo, [FLandscapeEditDataInterface](API\Runtime\Landscape\FLandscapeEditDataInterface) & LandscapeEdit )